Added the UUGear WittyPi 4 Power Management Board

src/en/overlay/uugear-witty-pi-4.md

@@ -0,0 +1,58 @@
+<!--
+---
+name: Witty Pi 4
+class: board
+type: power,rtc
+formfactor: HAT
+manufacturer: UUGear
+description: Realtime clock and power management for Raspberry Pi
+url: https://www.uugear.com/product/witty-pi-4/
+github: https://github.com/uugear/Witty-Pi-4
+image: 'uugear-witty-pi-4.png'
+pincount: 40
+eeprom: no
+power:
+  '2':
+ground:
+  '6':
+  '9':
+  '14':
+  '20':
+  '25':
+  '30':
+  '34':
+  '39':
+pin:
+  '3':
+    name: SDA
+    mode: i2c
+  '5':
+    name: SCL
+    mode: i2c
+  '7':
+    name: Power Button
+    mode: input
+  '8':
+    name: TXD / Off detection
+    mode: output
+  '11':
+    name: LED / SysUp detection
+    mode: output
+i2c:
+  '0x08':
+    name: ATtiny841
+    device: ATtiny841
+-->
+# Witty Pi 4
+
+Witty Pi is an add-on board that adds realtime clock and power management to your Raspberry Pi. It can define your Raspberry Pi’s ON/OFF sequence, and significantly reduce the energy usage. Witty Pi 4 is the fourth generation of Witty Pi and it has these hardware resources onboard:
+
+- Factory calibrated and temperature compensated realtime clock with ±2ppm accuracy.
+- Dedicated temperature sensor with 0.125 °C resolution.
+- On-board DC/DC converter that accepts up to 30V DC.
+- AVR 8-bit microcontroller (MCU) with 8 KB programmable flash.
+
+## Virtual Registers for Temperature Sensor and Real-Time Clock
+
+The temperature sensor and Real-Time Clock are accessible through the WittyPi 4 I2C device address (0x08), and are mapped to so called virtual adresses. The LM75B temperature sensor is mapped to #50 .. #53, while the PCF85063A Real-Time Clock is mapped to #54 .. #71. More details can be found in the [user manual](https://www.uugear.com/doc/WittyPi4_UserManual.pdf).
+